As for the probability of victory for a team that has already scored 1 goal, then it is necessary to collect reliable statistics. Has anyone collected such statistics?
"Even if you win 3 times in a row on bets with odds of 1.3, then 1 loss is enough to destroy all your winnings."
That is probably the best explanation why this "strategy" won't work out long-term. Coincidence can be running against you all the time and what Julien_Olynpic brought up here is important to consider. Even if you find one game with odds of 1.3 where you think that the bookmaker is getting it slightly wrong to the players' favor, in the long run if you play 100 games with odds of 1.3 the bookmaker is also less likely to get it wrong, meaning that the remaining margin for the player (if there is any) will approach zero, the more games are being played at that odds range.
@cybron wouldn't the best way to find out be to simulate it? You could go for it and behave "as if" you were placing bets exactly as you described and then share the results here. I am quite sure that over time the strategy will play out against you. The problem is that you shouldn't even vary your bet size, which makes it boring as it would purely be a bankroll game, hoping that due to pursuing that strategy you got an edge over the house. But I have seen 1.3 go wrong so many times that 3-way-parlays aren't even that promising at all.